Injectable compositions containing triamcinolone acetonide have been available for many years. Commercial products include Kenalog®-10 Injection (triamcinolone acetonide injectable suspension, USP) and Kenalog®-40 Injection (triamcinolone acetonide injectable suspension, USP), which are marketed by Bristol-Myers Squibb Co. These products contain 10 mg/ml or 40 mg/ml of triamcinolone acetonide, respectively. According to its package insert, Kenalog-40 Injection is approved for certain intramuscular and intra-articular uses. Where oral therapy is not feasible or is temporarily undesirable in the judgment of the physician, Kenalog-40 Injection is indicated for intramuscular use in certain cases for endocrine disorders, rheumatic disorders, collagen diseases, dermatologic diseases, allergic states, ophthalmic diseases, gastrointestinal diseases, respiratory diseases, hematologic disorders, neoplastic diseases, and edematous state. The specific approved ophthalmic indication is “[s]evere chronic allergic and inflammatory processes involving the eye, such as: herpes zoster ophthalmicus; iritis; iridocyclitis; chorioretinitis; diffuse posterior uveitis and choroiditis; optic neuritis; sympathetic ophthalmia; and anterior segment inflammation. Kenalog-40 Injection is indicated for intra-articular or intrabursal administration, and for injection into tendon sheaths, as adjunctive therapy for short-term administration (to tide the patient over an acute episode or exacerbation) in the following conditions: synovitis of osteoarthritis; rheumatoid arthritis; acute and subacute bursitis; acute gouty arthritis; epicondylitis; acute nonspecific tenosynovitis; and posttraumatic osteoarthritis.
Recently, the use of Kenalog®-40 Injection to treat diabetic macular edema, has been growing more common. In this use, the product is injected into the vitreous of patients suffering from diabetic macular edema. In some cases, the product is processed by the physician or pharmacy in an attempt to remove the preservative that is present in the Kenalog-40 Injection formulation supplied by Bristol-Myers Squib Co. (i.e., benzyl alcohol) because the preservative may be irritating to the vitreous and tissues in the posterior segment of the eye. Additionally, the commercially available product must be used immediately after it is shaken to avoid settling; the package insert reads as follows: “After withdrawal [from the shaken product vial], inject without delay to prevent settling in the syringe.”
What is needed is an improved triamcinolone acetonide suspension composition that is suitable for injection into the eye, does not settle rapidly, and can be easily injected through a small needle that offers the potential for a self-sealing puncture wound (e.g., 27-gauge or 30-gauge).